Sanitary filter



Nov. 9, 1948.

D. R. BABBITT SANITARY FILTER 7 Shets-Sheet 1 Filed April 26, 1945 &

Janet L Nov. 9, 1948. D. R. BABBITT 2,453,613

SANITARY FILTER Filed A ril 26. 1945 v i 7 Sheets-Sheet 2 ,Zizz/erziorf $872166 1?..5 iii' ,7 W, M f I D. R. BABQITT SANITARY FILTER Nov. '9, 1948.

7 Sheets-Sheet 3 Filed April 26, 1945 .Zizzieraivr. I jazzed Rfiazit 9,1948? D. RQBABBITT 2,453,613

' SANITARY FILTER Filed April'26, 1945 r 7 sheet' -sh'eet 4 lllllllll m.mmmum... 7

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Nov. 9, 1948. D. RBABBITT SANITARY FILTER Sheis-Sheet Filed April 25,1945

Nov. 9, 1948.

Filed April 26, 1945 7 Sheefs-She et 7 Jade/2 07.

Patented Nov. 9, 1948 v UNITED STATES PATENT SANITARY FILTER arilel KBabbi tt, San Francisco,Calif.,assignor 'to Electric steel Foundry; Portland, Oifgi, fafifl corporation of Oregon .App'lication'April 26, 1945;. serial-No. 590395 The present inventionrelates t'o-sanitary filters; and. is. particularly: concerned with. filters that are peculiarly adapted to: be used for work in: connection with: thefiltering of humanblood albumin and; otherlaboratory and sanitary processes; l V l 1 'One; of the objects of the. invention. is; the -p-rvision of animproved filter structure of the class described, all: of the parts at which are adapted to be readily assembled or taken apartand adaptedtot be sterilized: and. wiped clean so that the product which has been passed through the cleaned and sterilizedr filter may be absolutely sterile.

v Another object of the invention isrthe provision of arr-improved filter structure of the class described" which may be; utilized with various types of filter media and which may be embodied in filters having various amounts of filter surface,

and which is adapted: to be utilizedboth: for pressureandfor vacuum filtering.

Anotherobiect ofi the-invention is;the improvewill be apparentlfrom lthe following description sevensheets;

mentotfilterspf theclass described by providing a; structure whichhas no-cracks-or pitsor overlapping wires where small" deposits of bacteria or organic matter can lodge; and: in. which the exposed parts can be machined all over so that there arenoreugh cast surfaces that Will be difiicult to cleanandlto maintain in a sterilecondition.

Another object of the invention is the provision of: an improved' filter unit comprising a frame which isnprovidedwith suitable inlets and outlets and with foraminous filter plates against which the-filtering medium isto be supported, the filter Another object: of the inventionis the provision 3 of. an improvedzfilterstructurewhich may be conveniently separated and sterilized and which is alsoura'dapted to be, embodied in assemblies for single sheet filters, multiple sheet filters; double stage filtration, or triple stage' filtration, or a multiplicity ofstages, all by theuse of similar types of units thatmay be assembledto-produce these structures. l

Other objects and advantages ofthe invention different filtration stages; l

and the accompanying drawings, inwhiclh similar characters of reference indicate similar parts throughout the several views Referring to the drawings, of-

Fig. 1 is aside elevational view filter embodying the-invention Fig. 2 is atopplan view of the filter assembly of Fig. 1;; J v f i Fig 3 is a diagrammatic sectional view takenon ar plane passingthrough the axis and. through the inletand discharge ports of a single sheet filter assembly i w v Fig. l is a view similar to Fig. 3 of a multiple of a two 1 stage sheet filter assembly;

filter assembly;

Fig. 5 is a View similar to 3 ofjatwo stage filter assembly; N 1 a Fig- .7 V is a front elevational view of; one of the closed filter frames which is utilized for theends of the assembly; i 1

8 is asectional View taken. on the'plane ofthe line 8--8 of Fig. 7, lookinginthe direction of thearrows; f

Fig. -9 is a fragmentaryseetional view, taken on the plane of the line -9 ofFig. looking, iii-the- Fig. 6 is a View similar to-Fig. 3 ofa triple stage direction pfthe arrowsg, 1 it i Fig. 10. is a iragmentary' sectional View; take on the plane: of the line (I'lll 0- of Fig. 7, looking;

in the direction-ofithearrows; i l l Fig. 11 is a plan View of'one ofthe apertured er late h Fig. 12 is a plan viewof one of the snap-rings for holding the filter-plates: inthe frame;

Fig. .13 is aplan V-iew of oneoi" thesepar-ation grid-s or spacers for the filter plates a i Fig. 14 isa front :elevational view of one ofltl-i'e cl'osedfilter unitframes:which isutilized to sepa-- rate the various series: of .openwf-rames from each: other to formdiffierent 'filtrationstages;

Fi 15 4s a sectional view take'rr the plane 0f thel-i'ne l 'i fi bf-Fi'g. 14 Ibbkillg intl'iedi'lfc tionof shear-rows; l it V Fig. 16 is a"fragmentary-sectionalView;taken on'th'e pl azie or the. linel fie l'b of Fig. 14, showing how certain of the conduits are" plugged: in the separation" frames to" divide the assembly into Fig. 17 is .a front elevational View, in. section, of! one of openfi'rames which isluti lized. between the closed frames and separatio framestoform a fi lterassemblyg, r

which: there are Fig. 18 is a sectional view, taken on the plane of the line l8l8 of Fi 1'7;

Fig. 19 is a fragmentary sectional View, taken on the plane of the line Ill-l9 of Fig. 14;

Fig. 20 is a fragmentary sectional view, taken on the plane of the line 20-20 of Fig. 14;

Fig. 21 is an. end elevational view of the filter assembly of Fig. 1;

Fig. 22 is a fragmentary sectional view, showing the mode of assembly of the various frames to form a filter assembly;

Fig. 23 is a fragmentary sectional view, taken on a plane passing through the axis ofa conduit of a filter assembly, showing the mode of assembly of the parts at this conduit to providea twostage filter, taken on the line 23-23 of Fig. 21.

Fig. 24 is a similar fragmentary sectional view, taken on the plane of the line 24-24 of Fig. ,21, passing through another conduit of the assembly,

showing how the separation plate or frame may b'e used'to divide the assembly into two series or sections or stages. -Referrin'g'to Figs. 1 and'2, these are side elevational and top plan views of anexemplary filter assembly, indicated in its entirety by the numeral 30. This assembly preferably includes a pair of pedestals 3|, 32, one of which is shown in front elevation in Fig. 2'1, and thepedestals are provided with a plurality, preferably three, supportingtie bolts 33-35 (Fig. 21) The two pedestals may be similar in construction, and each consists of a substantially rectangular member having a substantially rectangular aperture or cutout 36 for the purpose of reducing weight,'and formed at'its-lower end with a pair or feet 31,38, with forwardly and rearwardly extending foot flanges 39, 40 for increasing the area of the lower plane supporting surface 4|.

The pedestals 3|, 32 are provided with apertures at the upper corners for receiving the supporting tie bolts 33, 35, and with anaperture centrally'lo'catedbetween their sidesin the lower supporting frame member 42 (Figf2l) for supportingthe lower tie bolt 34in a central position. The tie bolts 33-35 are preferably of thestructure shown in Fig. 1, each bolt being provided withan' elongated cylindrical shank'portion 43 providedat its left end in Fig.1, with an enlargement or intermediate head 44, which may {be cylindrical, and which has the annular thrust surfaces 45; for engaging the pedestal 3l and the left end of the filter assembly.

Beyond the head M the tie bolt 34 is provided with a threaded portion 41 and a clampingend 58 so that the pedestal 3l' may be clamped between the nut and the annular surface 45. At its opposite end the tie bolt 34 is provided with a threaded portion 49 and with a reduced cylindrical portion 50 which is also threaded and providedwith a nut Between the two threaded portions 459 and 50 there is an annular shoulder 52, which engages the pedestal 32...Thus the pedestal 32 is clamped between shoulder 52 and the nut 5|, and the structure of the other tie bolts 33 and 35 is similar, and they are secured tothe pedestals 3! and 32 in the same way.

' Thus the pedestals and tie bolts constitute a supporting structure upon which the filter press it will be seen that there are two of the end press 4 emplified in Fig. 17, indicated in its entirety by the numeral 60.

Another form of filter supporting element is the closed separator type of screen frame shown in Figs. 14 and 15, and indicated in its entirety by the numeral 6!. A third form of filter supporting element is the stationary end press plate of the type'shown in detail in Figs. 7 and 8 and indicatedby the numeral 62.

Referring now to the filter assembly of Fig. 1,

plates which have been indicated by the numerals 63a and 63, one separator frame Bl, which separates'the filter. assembly into two stages, and a multiplicity of the'open screen frames on each side of the separator frame 61. For example, there are six screen frames on the left side of the separator frame 6| between this separator frame and the press plate 63a.

All of the parts of the filter assembly, including those previously described and those further to be described, are preferably made out of noncorrodible metal adapted to receive a smooth polished finish, such as,'for example, stainless steel, and so far as possible rough surfaces as cast are eliminated from the filter parts, particularly those parts which come in contactwith material to be filtered, so that they canbe wiped clean andsterilized to maintain bacteriologically sanitaryconditions. 1

1 Referringnow to Figs: 1'7 and '18, thisis' one of the open screen frames,-'and it preferably o'om prises a substantially annular member fiflwhich has an inwardly extending centrally located' rib' 64 with annular surfaces 65 and fit on each-side of it. Theinner surface of the rib may be cylin-- dri'cal at 61, defining a cylindrical through bore, and at each end of the screen frame through bore 61 communicates Withcounterbores 68, 59. Each of the counterbores 68, 69 is provided adjacent the thrust surfaces 65 or 66 with an annular-g'roove 10 which is concentric with the borefil, and the grooves 10 are preferably substantially semi-cir-' may be supported. The tie bolts may also be plurality of types of filter units or filter supporting elements. Among these units the most commen one is the open-screen frame of the type excular in cross section so that they are adapted to receive thesnap rings H (Fig. 12)

The snap rings H are preferably made of plate metal, and are flat on one side and of such cross section that they are formed on a radius of a circle on'the opposite side. Each snapring is formed to a circle which is' substantially larger than: that of thegroove in which itis to be placed so that the rings are tensioned to spring-outward into the groove, and each ringmay cover almost the complete circumference of a groove. The ends of the ring are open, and are provided with radially inwardly extending portions 12,13 between which a tool may be inserted, such as a screw driver, so that the-tool maybe-twisted to force'the ring out of its groove. T The size of each ring in relation to thegnoove l0 isprefe'rably'such that when 'a screen sheet M (Fig; 11) is placed in one of the-counterbores 68' or fis against the annularshoulder 65 or; there is still space in the groove '10 so that the snap rings may spring out into tlie'groove'; The round portion of each snap ring is then on the outside, and as it engages ther'ound surfaceof the groove it tendsto force itself outwardly far ther into the groove and-atthe same time :to

cam the screen sheet inwardlyagainstthe'an- -As the snap rings overlap the tosenve as conduits.

screensheets, these rings are adapted to hold the 'screen sheetstightly in the filter frames, and

each open swarm-met: thetype 69, shown in Fig. 17; is provided with a pair of such fscreen sheets and snap rings. f

The screen sheetsare preferab1y made of thin sheet-metal, such as, forexample, No; 26-U. S.

gauge sheet, and these sheets are perforated with relatively small diameter holes, such as, for examp1e,-one-sixteenth of an inch diameter, all of the perforations being kept within a predeter- 'mined margiri, which isdetermined by thesize of the -bore 6T in the frame, and locatedfverytclose to each other. wForexample, in one embodiment of theinventionrthere-are approximately 100 holes tothe the "holes being square inch, and witha seveninchinner diameter area for theholes; the total numberof holes is approximately-3,987 The holes are smoothly shaped; and all :burrs are i removed 1 so that such screen sheetscan be wiped clean, and any foreignmatter which happens to lodge in the holes rality of. radiallyextending lugs 19; 80, 81,82,

which are of suflicientsizeiso that they may be provided with through bores 83; 84, 85, 36 adapted ,The external shape of the lugs l982 may vary considerably, but they are preferably provided :with partially cylindrical outer surfaces 81, which are also provided with concavely filletedportions 88 at theirjunctures with the outer cylindrical surface 89.0f the screen frame, Thus the externalsurfaces are. easy to clean. 1 ,1 Certain of the through bores, as for example 83 and 85 in the lugs 19 and 8|, may be used to supportthe screen frame tubes 90, 9| comprising short lengths of ,metal tubes having inner and outer cylindrical surfaces and of sufiicient length to project beyond the screen frame at each side, as shownin Figal8.

'Ihe projecting portions 92, as or the tube 9| 18 project sufliciently so that they, may be received in bores of adjacent frames of the type 94 3.1101 86 without, however, extending over or closingtheconduits 94, 95 (Fig. 18), which proyide communication between the bore 610:? each screen frame and the conduits 84 and 86. 1

,-,;'lhes-econduits 94 areshown in Fig. 1'7 as extending radially inwardly, from the bore '61, there being three conduits communicating with the cone duit 8 6, and the ring is :preferably'provided with a relief ,or cut out'95 wherever drilledradial conduits94 are located; In; the same way, drilled nicationbetween ,thebore 61 and the conduit 84 inlugt ll. H i 1 i Some of the screen frames 60 may have their conduits 84 provided with a threadedbore 91,0n its upper side for use in communicating withinlet pipes,-outlet pipes, or pressure gauges, or the like; but the majority of the screen frames, where many are used, need not have the bore 91. v

I conduitsiili at the top of Fig 17 provide commuscreen frame, but, if not, it preferably has a tight frictional fit in the bore 83 or 85 ysothat was fixedly secured in the screen' frames. The fit o f the projecting end portions 92, 93 ofieach tube 9! in the adjacent bores 8 '4, 86 of the adjax'ient screenframes is not of importance because the leakage out of the assembly isiprevented there;v between by the clamping of the filter element between the frames, after the manner of: a gasket; i Each screen frame is preferably provided with the substantially plane end surfaces 98,9950 that the screen frames. may: be assembledJadjacent each other in such i'manrieri that filte'r elements maybe clamped between each surface 98 andithe adjacent surface 99 of another frame The surgfaces 98, 99 are, howevenpreferably providedlwlth annular grooves I99; 1 I 9| located inwardly :of the conduits 83-85 and concentrically; wit respect to the through bore 67. i 3 i The grooves I 00, lfll separatetitheplane n surfaces 98 and 99 on eachifaceqof the-screen frames into two portions, an outerhportion 1.02, I03, andflan inner clamping'portion M43195; for engagingthe filter medium. Ir ztl Various types of filter media maybe employed,

such as, for example, in the first stage a filter paper maybe used for eliminating theiglutinous substance and constituting a clarificationsection. Inthe second stage of the filter a bacteriological filter medium may be used which removes on bacteria. These filter media are generally :indicated by the numeral 1 0B inthe filter assemblies, and they are located between each of theiisci'een frames and between each? endmost screen 1i frame and the adjacent separator frame, or press zplate.

Each screen frame is alsopreferablyiprovided with spacer means located in the: bore' 61 601 maintaining the spacing of the twoscreentplates 14. Thespacer meansis preferably of the *same metal and is of such shapethat it can be easily cleaned,'and such a spacer is shown in Figr'13.

It comprises a spirally formed circular wwir e, the outer convolution of whichissmaller ithan the bore 61. The diameter of thewire isipreferably equal to the length :of thebore 67 ,"that is, the distance between the annularsurfaces 6'5 and 66, such as, for example, '33" anduth'e outermost convolution may be turnedinwardly at its end "so that theoutershape of the spacer is substantially circular. i 1 a. iv.

The spiral coilspacer indicated in it's' en tirety by the numeral 1101 .(Fig. 13). ohe such spacer is used in each screen frame fifl t'o prevent the screen plates 14 from collapsing against each other f .i, ,i i

Referring to. Fig. .14, this separation' framelil is similartothe open screenframe 60in itsexternally shaped hooked supporting lugs '15; H16 and projecting, lugs: 19-:--82 with-conduits.It differs from the open frame 60-: in thatthere is no bore '61 :wbut, on the contrary, there is an integral partition 108,1 whichcloses one counterbore 68 from the other counterbore 69 (see Fig4'15). The partition is provided with a cylindrical recess I09, ,I Ill on each side, ,and a plurality "of drilled conduits ljlluextend from the recess 109 to the conduit, H2, axplurality of similar drilled recessesextend from the recess I III to the conduit 2 (see Fig. 19). 1 j In this case the bores 83 and 85 are preferably plugged with a solid, cylindrical member I M (Fig. 16),.while both the, conduits ll2jand1I5 have the drilled holes] I I andd 13 providing. communi the partition I03.

The drilled holes III, I'I3 extenddiagonally in this closed screen frame;- and the closedscreen frameitl is adapted "to separate the filter press into two stages; i

:l'teferring'lto Figs. 7 and8, these are views of one of thedandpress plates, upon whichpressure is exerted by various threaded members for making, the assembly liquid-tight at the joints be tween theframes; The ,end press plate, illustrated in Fig, 7, maybe plate 63a of Fig. -1, and it'lis preferably constructed as follows. This end pressjplate consists of a substantially cylindrical metal member, which again has the laterally projecting hook lugsIE, I6 and thefour radially projecting lugs 19-82.-provided with the through conduits 83-86; In this case theendpress plate is of substantial thickness,;and is preferably provided' with additional upper and lower bolt-engaging lugs H6, H1. -The'upper lug H6. is provided with a-bore I i8 for receivinga clamp bolt I I9. The lower lug I I1 maybe forked, .having a slot I20 so that it may be placed over the shank of bolt 34 carried by a pedestal 32. Thus the and press plate63a; has a three-point support'on the tie rods that arexcarried' by the pedestals. 1 r i In order: to providemaximum strength, with minimum weight-the end press plate 63a may be provided with a plurality of annular reinforcing ribs I23,- I24 on its rear side, leaving-annular grooves I25, I26 and a cylindrical recess I121.

Theannular. ribs I23 may stop short of the rear surface of the endpressplate 63a so that they engage .a cover plate I28 of sheet metal, which is rabbeted in a :recessI29 in the end press plate and secured in place-by weldinglor other means of ho'ldingsuch assoldering, screw pins, etc.

.Thus therecesses in the rear side of the end press plate. are closed and made liquid-tight so that there can beno access to these recesses by foreign matter. Thesheet metal plate which closes them is,'ofxcourse, easy to clean, and permanently attached.- v I The other. sidetof the'end press plate 63a is pro- .vided with a'circular dished recess I30 and with the same counterbore 68,,previusly described, for the openjframes; and with the same groove ll] of circular cross section, for receiving snap wire. Drilled holes I3I extend radially from the recess I3.II to conduits 83 and 85 so that a screen-plate 14 may coverthe face of the recess I30, to provide abaeking for afilter medium,-.and-the liquid which filters through it is discharged through conduit85, through drilled holes I3I. 1 1

In every case the screen sheet I4 is supported against bucklingby a spacer, I01. Referring now to Fig; 22, this'figure shows a fragment of oneofthepartsof-a plurality of frames provided'with spacers,snap wires, screen sheets, and the filter medium inbetween each pairof frames. Thisris exemplary of the construction of the filter assembly-throughout.

Referring now=to Figsl 23 and 24, these are views-showing the inlet and outlet conduits'and showing-the alternate arrangement of the frames so that-the tube ill in one frame extends into the unfilled conduits of similar location in the other frame, which is merely reversed in position.

The way to provide the alternate arrangement of the frames so that the'tube 9I inone' frame extends into the unfilled conduits of similar location in the other frame is to invert a frame of the type of Fig. 18. When the frame is inverted, the-empty conduits will then appear at the right in Fig. 18. The frame is then in position'to entop.

gagethe projectingportions 92,- 93ofthe tube SI, of the frame which has not been inverted-and shown in its normal position in Fig. 18.

; Thus an assembly'of screen frames may be arranged with the frames alternately reversed in position so that tubes SI provide communication between the' aligned bores 84, 86in the adjaqent Fig. ,24', suppose the conduit, which is indicated, in itsuentirety, by'the numeral I35, is an inletconduit formed by the. aligned tubesand bores in the various frames, the fluid coming'inat the left end would pass downward through the apertures I3I in the end press plate 63a into the cylindrical depression I3il,.thence through the'screen plate Ma, and filter medium I06a, and through the screen plate 141), into the bore 611) of the first open frame, which is indicated by the numeral It will be noted that the tube 9%. at the top of this screen frame 6% merely provides a part of the conduit I35 and has no drilled holes communicating with. the bore 61b l Before showing how the fluid passes out of the space 611), we shall continue with other screen frames and show the course of fluid into these spaces. Additional parts of the'fiuid may pass down the conduits 96c into the space 610 in the open screen frame 600. Y I

This fluid may pass toward'the left and the right, and that which passes toward the left will go through the screen plate'Mc and through the filter medium I060, and through the screen plate 14b, which is located on the right side of the bore 611), and thence into the bore 611). Additional fluid which passesinto the space 610 will go to the right through two screen plates and the intermediate filter medium into the space at 51 l. 1

It will thus be observed that in so far as the open frames are concerned each alternate one is incommunication with the conduit I35 at the Referring now to Fig. 23, let us suppose conduit I35 is serving as an outlet conduit. The liquid which has passed into the bore 61b in Fig, 24-can now pass outof theapertures into conduit I36. Liquid which has found its way throughscreen plates and filters to the space 61d can paiss'out of the drilled holes 94d at the top of Fig. 23 into conduit I36.

Thus it will be observed that the'ffilter media which are carried between these end' press plates and the adjacent 'open'screen frames are: con-'- nected in parallel, and the amount of filter sur= face available may be'incieased by usingmore screen frames and filter'media between them,

Referring now to Fig. 24; and in particulate the separation plate 6|, conduit I35 "is 'closedby means of a plug H4 in this separation platel This prevents liquid in the left end of conduit I35 from passing into the right end except by'g'oing through another series "of filter plates.

Referring to Fig, '23, it will be observed that the outlet conduitl36 is open from end to end. Its ends may, ofcourse, beclosed'by'suitable plugs, or may be connected to a container for theflltrate.

. I 9 I Arrows have been drawn on both of these figures to show the course of the fluid through the filter press.

When conduit I35 is used as an inlet in a multiple sheet filter, as illustrated in Fig. 4, no separation plate BI is used, and the right end of the inletis plugged, then, each alternatescreen frame is also used as an inlet at that side of the assembly. This means that frames 63c, 60c, 60c, 50a, 5071., 607, 501 and 6071. have inlets 95 from the conduit I35.

Every other alternate frame as shown in Fig. 23, at the other side of the frames, is used as an outlet member. Thus the frames 60b,,60d, 60f, 6|,160i, 60k, m and 63 serve as outlets to the conduit I36.

The assembly shown in Figs. 23 and 24 may be used as a two-stage filter by using one end of conduit I35as an inlet, that is, the left end; and

the other end, that is, the right end, as the outlet.

duit I3B-which is at. the left of the separator plate BI. Thence the fluid passes over into the right- ;hand part of conduit'I36 into the frames which are located at that side and which are provided with suitable conduits communicatingfwith the right end of conduit I35, which may be the outlet. In order to provide for the relatively quick separation of the frames and quick and very uniform clamping action on the frames,.the right end of the assembly (Fig. 1) is preferably provided with a clamp bar I50, which is arranged to engage the tie bolts H9 and 34. This clamp bar comprises an elongated metal member having a hub II at its upper end provided with a bore for passing the tie bolt H9. At its opposite end it has a hub I52 provided with a slot I53 extending laterally into the hub and terminating in a rounded portion adapted toreceive the tie bolt 34. The hubs I5I, I52 are each provided with plane end surfaces I54, I55 so that when the clamping nuts I56 and I58 are driven home on the tie bolts 34 and I I9 the clamp bar I50 engages the assembly of frames and causes them to clamp the intermediate filter media between them.

When the nutson thesetie bolts are loosened, the clamp bar I50 maybe pivoted in a counterclockwise direction in Fig. 21 to release the tie bolt 34 from slot I53, whereupon'the filtertassembly may be lifted from the pedestal assembly. The tie bolts and 34 may be provided with intermediate nuts l56 and clamping ferrules I51 so that they may also exert a clamping force upon the complete assembly.

Referringnow to Figs. 3 to 6, these are dia grammatic illustrations showing how various types of filter assemblies may be made. ,InFig. 3, 63a, indicates one press frame, and 63 the other; Iflfiindicates the filter media. The frames are so arranged that the inlet is at the bottom, the fluid to be filtered passing into the space I of one press plate, through the screen plate (not shown) filtermedia I06; and the. other screen plate (not shown) into spaceISIi; and

thence out of the outlet at the top of the assembly.. Thus two press plates may be used to make a single sheet unit. n

In Fig. 4, this is a diagrammatic illustration showingamultiple sheet filter. In this case the inlet is at the bottom and theoutlets are all at the top, and a multiplicity of the open frames 6 a d e is atthe right, bottom.

filter media .I 06 are employed, but there sweep; arator frame. I

Referring to Fig. 5, this is a two-stagefilter as sembly in which there are more frames utilized in the pre-filtration stage than in the secondfiltration stage- Here the inlet is at the bottom left, and two endpress plates 63a; and 63, areused,

Referring to Fig. 6, thisis an illustration showing a multiple stage or triple filtrationgassembly. The first stage extends fromthe prtss plate 63a to separator plate Bio. and also includes the intermediate open frames 60a, 60b. The second stage extends from the separator plate 6m to theseparator plate BIZ) and includes the openframes 60c, 60d. The third stage extends from the sep; aration frame Glb tothe end press plate 63 and also includes the open frames 60c and GUI.

Referring to the arrows showing the direction of flow, it will be seen that the liquid flows in at the bottom, up to the top, down to the bottom again, and up to the top. In any particular filter and sterilized. The assembly is readily disassem I bled, it can be polished, and it can be as easily put back to ether. There are no screens having. crossed wires or other parts which haverecesses that are difficult to clean and apt to collect foreign matter. The screen plates are made of I sheet metal, provided with a multiplicity of per? forations, and they are supported ,by spacers of spiral wire, which are also easily cleaned." Since the inside of the screen framesiscircular; itmay be machined to a smooth surface and. polished at a. minimum expense, and the filter elements are adapted to be cleaned without difficulty.

While I have illustrated a preferred embodi- H ment of my invention, many modifications may be made without departing from the spiritof the invention, andI do not wish to belimitedto the precise details of construction set forth, but.

desire to avail myself of all changes within the scope of the appended claims. 9 Having thus described my invention what I claim as new and desire to secureby llletters Fag ent of the United $tates is: I

1'.'In a sanitary filter structurefla filter unit which, in combination with a co-acting part of the filter structure is adapted to gripkthemar ginal portion of a filter medium, said filter unit comprising screen plates, a metal frame provided with a through bore of circular shape, a counterbore at each end of said frame for supporting a screen plate, and an annular groove in each end of the metal frame extending axiallyinto the frame in radially spaced relationship to the counterbore and concentric with the through bore, the end surfaces of said frame between the an- I nular j grooves and the counterbores providing 53. The outlet iaccntthc coun erboresl the. cre n P ate in ach counterbore engaging one of said annular shouldata of: the. trams he axia h ines each 0 1 ho bein provid d. with. a ahnu a groo rv o the hrou h here an xtendin I I into the axiai surface t the cpunterbore, ar ilient' shrine. mem er l ca ed n each. o d co n e 'bor gr ov s. a f sai r ng m m er e ndin nward oward he thro g bore tram on oithe gr ov sufii ie to ove lap t e margin. of the screen plate and retain it in the rame agai st. he f sa d hou ers,

2,. I ani ary lter s uctur a filter u i which, in m i a i n ith he. c r-a tin p o the filter structures, is adapted to grip the mare sihal. ortionci filter m di m said filter u comprising screen lates, a e a ame provid with, i h' olish bor of lar hape, a counterbore at. ch: e d f a d. f am or su port ng a screen ate, and an an u ar r o ex n n axia l nto. ea h. nd. of the meta ame and dpitsled rt dially of the counterbore in concentric relationship to the through bore, the frame end surface between the annular groove and the counterbore providing a clamping surface for saidfil-ter medium, the counterbores at opposi e ndsof thei ame being ep ated by a p tion. of; the-frame extending inwardly in a radial direc ion and p vid n an u a ho lder a the innerendsof the connterbores, the screen plate n e h counter o c en a n wo d a u ar shoulders and being carried by said frame, the ax alur ace a h h h erhhre ei g Provided wit n nn lar ov onc ntric h the throne-h; h e a r s l n rin m mbe at insach of thecounterbore grooves, each of said sari a memb rs e t nd nwa d y w r e through bore from one or the grooves. sufficiently tn oyerlapthe margin of the screen plate and re a n, t t rame an n t ne of a d shoulders, eachof said resilient spring members heiherr d d w th a a u a On t d engaging thescreen plate and with an outwardly diverging surface on its Opposite side for wedgeike rs' eem n n th ove.

3, Inasanitaryfilter press assembly including a supporting member consisting of a pair of pedestals, the said pedestals being joined bya P111 313 of tie rodsfafi lter'press structure carr nd b aid he dsla c inr s ar of end press plates, the said end press; plates being plfqvi ded with projecting slotted lugs engaging a pluraiity of said tierods for supporting the phess, plates, each press plate also being provided with passages and'a conduit'adapted. to be used forifiiild inlet or outlet, and each press plate having: therein an annular counterbore. terminating near a wall and defining a Substantially circular jecessbetween the. end'of: the counterbore and sa d we l a pl ra t perforat d sc en p -t a ne an p rf r ted cree p at s fi ing nt hewunt rhor htle ch re Pa n c n the recess tl e axial surface of the counterbore. of press pl-ate-alsoghaving an annular groove paced from an daconcentric with the Wall, ahimv a pring wire located in said groove in each Pre s la or h di g e h r en la Place against the nd s r ace f the t ht rb r er bein also apl r l ro r n rec a Screen f am oc ed between aid P ss lat s, e ch of id or E scre n frame hav n a h u h bore, ai Qfifih flame so he -7 s c t r ed a e h end f s, the re at nsh p to th irthroueh ores saidc r ttthores h irs separa ed y n inwar y extending annula f ame. mar ian pr vidin hou ders and a sc een Plat lo a ed gain t h of sa d. houlders ach. or said fram un bores also having an annular groove in the a ial suri q h eo n co ce tric w t e through bore, the latter screen plates being secured against said shoulders by resilient mems s r n into sa d nn l gro v in h en frames, a spirally formed spacer between said screen plates, and there being a filter medium between the end face of each press, plateand the end face of the adjacent open screen irame and between th opposing end faces of eachpair of screen frames so as. to receive and support the filter medium against movement, and said passa s ro di n e tio s r co mu ication between said conduits and recesses whereby fluid to be filtered may pass in one end plate threagh the filter media and open frames and out of the oth r press p ei 4, In a sanitary filter press assembly including a supporting structure consisting of-a pai of pedestals joined by a plurality of tie rods, a' fi-lter press structure carriedby 'said tie rods and comprising a pair of end press plates, the said end press plates being provided with projecting slotted lugs engaging a plural-ityofsaid tie rods for supporting the press plates, each press plate also being provided with a conduit adapted to beu'sed as a fluid inlet or outlet, and ach press plate having therein an annular counterbore terminating near wall and defining a substantially circular ecess betwe athe or the count t.

said wall, a plurality of perforated circular screen plates, each of said perforatedscreenplates fitti e n o; h cunter nr t ch p s nae an covering the adjacent recess, the axial surface of he o n er qre Qt Pre s P a also hav n an annular groove therein concentric with and spaced from the wall, and a spring wire located in said groovein each press plate for holding each screen plate in place against the end surface of the counterbore, then; being also a plurality of open metal screen frames located betweensaid press plates, each of said open screen frames having a through bore and being provided at each end of the through bore with a plane annular thrust face, and a screen plate located against each thrust face, annular grooves in saidframes adjacent each of said thrust faces and concenrio w h t hr g bor e l ter scre plates being secured against the thrust facesbg resilient members sprung into the annular grooves in the open screen frames, spirally o m d SPWB T E be we n e c e n p ate .5 each ree ame, an h e ei a er m i m between each end press plate and the adjacent open r en, r me nd between ac pa r f screen frames, the open screen frames being e a a e nto t o e es, b a epa ator sla dis ose be w en th s en rames f the. series, said separator plate being integrally constructed to ovide n. ehhular side al a r r t o 'w exte in acro hr h b res Qifth screen name o the lt r P es ssembly and a onduit t ide. f. the s de Waltzi fl id. ras sesin said. p ess r and. separa or P a e. conn cting aid co duits to said rtcess and, he l aqes, adjacent. aid cr en. p ates. Q pp si e des of he. pa t ti n Welt. the a d. qondui sbeins. an heate and, a ran ed for 11. 9 1. w first h ugha plurality of filter media suppqrtedby the screen irames Pre s relates. on one s de i ricr ra er state then hro h. heccnduitoi hesera rater a e and th rea er rough a r' ural r Qt are: neq a sup r ed by, pl tes 13 on the other side of the separator plate to pre vide two stages of filtration.

DANIEL R. BABBITT,

Number Number 14 Name 1 Date Lieberich Mar. 12, 1907 Arendt et a1. Aug. 20, 1907 Woods May 27, 191 3 Demers July 18, 1933 Teatini Dec. 17, 1935 Sietz Apr. 6, 1937 Holt Sept. 26, 1939, Obenshain et a1. Aug. 14, 1945 FOREIGN PATENTS Country Date GreatBritain 1904 France Mar. 31, 1932 (1st addition to No.696,990) 

